Astronomy

How to Measure a Light Year



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Measuring the speed of light allows for a full appreciation for the size of the universe as well as the celestial objects within this phenomenal space. When thinking of a light year its important to remember that it refers to a measurement of distance rather than time. Learning how to measure a light year allows the full exploration of space measuring its scale in comparable views with a workable measurement of distance.

In terms of astronomy a light year corresponds to a measurement of distance rather than time. A light year in its purest form measures the distance a ray of light takes to travel in a vacuum from one point to another. This ray of light travels at approximately 186,000 miles-per-second (299,792.458 km a second) a speed which remains impractical to perceive. In essence the speed of light enables an object or person to travel around the circumference of the earth seven times in one second. Or another way of perceiving the speed of light is to travel to the moon and back (at its closest elliptic) in just three seconds.

To measure a light year it’s necessary to understand that its distance equates the distance light travels in a contained vacuum (space exists as a vacuum) in one Julian year. So understating that light travels at 186,000 mps it’s possible to calculate its length. The key concept of how a light year gets measures requires the understanding that the distance is equal to the time a ray of light travels in one human earth year.

186,000miles x 60 seconds = 1,116,000 miles

60 minutes x 1116000 = 669,600,000 miles

669,600,000 x 24 = 16,070,400,000 miles

16,070,400,000 x 365 = 5,865,696,000,000 miles in one light year or 9,439,922,663,424 km

The purpose for a using a light year as a term of measurement makes scientific as well as amateur astronomy easier to comprehend. When talking about distances its far easier to talk in light years than to add all the necessary zeroes to a distance to give a measurement in classical kilometers or miles.

In terms of astronomy defining the speed of light through practical measurements allows for the understanding of the distances for all celestial objects. Using conventional radio waves it’s possible to ascertain the distance by reflection of a celestial object. Once this radio wave distance is known it’s then possible to calculate the light year distance to understand the total distance to the object in question.

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